The goal of the proposed research is to define the natural history of perinatal cytomegalovirus infection in mothers, infants and children. Through prospective studies of pregnant women and their offspring, infants with acquisition of CMV in utero during both primary and recurrent maternal infection, intrapartal acquisition, and early postnatal acquisition will be identified. These infants, as well as matched controls, will be followed longitudinally throughout childhood. Their general health and development of intellectual, behavioral, social, visual, and auditory functions will be regularly assessed by a multidisciplinary team; both children and their mothers will be followed virologically and serologically as well. Specific cell mediated immunity to CMV as measured by lymphocyte blastogenesis and interferon production will be measured in mothers and children representing each type of perinatal transmission. The effect of both cellular and humoral immunity on clinical and virologic events will be determined. Long-term intellectual and perceptual development will also be compared in patients with different modes of perinatal acquisition of CMV.